Port knock of 445 prevents smbd from starting

[Jeremy Allison]

On Tue, Jan 14, 2020 at 09:26:24PM +0000, Christopher O Cowan - Christopher.O.Cowan--- via samba-technical wrote:
> In our cluster setup here, we use a load-balancer in front of our ctdb cluster to steer the SMB traffic.
> We've been doing this for years.    It does a simple TCP connect on 445 to verify that each node's smbd is still alive.
> 
> This is all on AIX, and some time, in the past few weeks these knocks started causing smbd to exit.   Here's the output from an smbd -i -d10.
> 
> First I see this (x.y.z.219 is the address of the LB.  202 is the server).    I changed the addresses
> 
> -----------------------------------------------------------------------------------------------------------------------------------------
> 
> Allowed connection from x.y.z.219 (x.y.z.219)
> Connection allowed from ipv4:x.y.z.219:49463 to ipv4:x.y.z.202:445
> ctdbd_control: Sending ctdb packet reqid=7, vnn=4026531841, opcode=23, srvid=17509995351216488448
> ctdbd_control: Sending ctdb packet reqid=8, vnn=4026531841, opcode=44, srvid=0
> INFO: Current debug levels:
> -----------------------------------------------------------------------------------------------------------------------------------------
> Then after the debug settings, I see:
> -----------------------------------------------------------------------------------------------------------------------------------------
> init_oplocks: initializing messages.
> Registering messaging pointer for type 774 - private_data=20141c48
> Registering messaging pointer for type 778 - private_data=20141c48
> Registering messaging pointer for type 770 - private_data=20141c48
> Registering messaging pointer for type 787 - private_data=20141c48
> Registering messaging pointer for type 779 - private_data=20141c48
> Registering messaging pointer for type 15 - private_data=0
> Overriding messaging pointer for type 15 - private_data=0
> Deregistering messaging pointer for type 16 - private_data=0
> Registering messaging pointer for type 16 - private_data=20141c48
> Deregistering messaging pointer for type 33 - private_data=2011cf18
> Registering messaging pointer for type 33 - private_data=20141c48
> Deregistering messaging pointer for type 790 - private_data=0
> Registering messaging pointer for type 790 - private_data=20141c48
> Deregistering messaging pointer for type 791 - private_data=0
> Deregistering messaging pointer for type 1 - private_data=0
> Registering messaging pointer for type 1 - private_data=0
> event_add_idle: idle_evt(keepalive) 20203538
> event_add_idle: idle_evt(deadtime) 202040b8
> event_add_idle: idle_evt(housekeeping) 202041c8
> read_fd_with_timeout: blocking read. EOF from client.
> receive_smb_raw_talloc failed for client ipv4:x.y.z.219:49463 read error = NT_STATUS_END_OF_FILE.

What version of Samba. These debug messages don't
quite match current master code.